Method and system for identifying paleozoic strata based on element differences overlying limestone

Abstract

The application provides a method and system for identifying paleozoic strata based on element difference of overlying strata. The method sets an overlying identification depth based on the true depth extension of the paleozoic strata before drilling through the identification selection step, and formulates corresponding sampling area selection strategies for different drilling areas. When drilling to the sampling area, the collected basic rock samples are picked and prepared to form test samples for element analysis. Then, the X-ray spectrum analysis method is used for element measurement, and the content contrast coefficient of the identification characteristic element of the paleozoic strata is calculated based on the measurement result. Finally, the identification element standard calibrated in advance is combined to determine the paleozoic strata pre-characterized by the current strata. The above scheme can overcome the defects of the prior art, such as the need for multiple sample detection at a single depth, and the lack of detection result accuracy and comprehensiveness. The category and position of the paleozoic strata are pre-identified based on the overlying strata of the limestone, which provides data support for the optimization of drilling and completion construction.

Description

Technical Field

[0001] This invention relates to the field of petroleum geological analysis and application technology, and in particular to a method and system for identifying Paleozoic strata based on elemental differences overlying limestone. Background Technology

[0002] In recent years, the Lower Paleozoic buried hill oil and gas reservoirs in the Chezhen and Zhanhua depressions have become one of the main areas for increasing reserves and production in the Shengli Oilfield. This region is characterized by well-developed faults and complex strata. The overlying strata of the Paleozoic buried hills vary greatly, especially the Upper Paleozoic Benxi Formation and the Lower Paleozoic, both of which contain carbonate reservoirs, with visual differences so subtle they are difficult to distinguish. To ensure drilling safety and meet the needs of later development, it is necessary to expose 1-2 meters of the Lower Paleozoic strata and install technical casing.

[0003] Currently, the identification process typically involves technicians making a preliminary determination of the Paleozoic limestone layer based on stratigraphic parameters. Further identification is then based on sampling and observation during drilling to pinpoint the Paleozoic buried hill's interface. However, the use of new technologies such as PDC drill bits and turbine drills in drilling often results in fine rock cuttings and severe damage to the original morphology of fossils, structures, and textures within the rocks and minerals. This approach can only determine lithology but cannot distinguish stratigraphic characteristics, making it difficult to accurately determine the stratigraphic position of Paleozoic strata and complicating the identification of buried hill interfaces. Therefore, existing identification methods have poor representativeness, cannot accurately and reliably obtain classification results for deep Paleozoic strata, and have a high probability of interface interception during the identification process. When manual prediction is inaccurate, multiple sample submissions for rock and mineral identification are required, delaying the drilling schedule.

[0004] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] To address the above problems, this invention provides a method and system for identifying Paleozoic strata based on elemental differences in overlying strata. In one embodiment, the method includes:

[0006] Before drilling, the actual depth of Paleozoic strata in different drilling areas is statistically analyzed. Based on the upper limit of the actual depth, the overlying identification depth is set accordingly. Sampling area selection strategies are formulated for different drilling areas according to the set depth intervals.

[0007] During the sampling process, drilling cuttings are directly collected as basic rock samples according to the sampling area selection strategy of the current drilling area, and then marked.

[0008] The sample preparation steps include selecting and preparing marked basic rock samples to form samples that meet the identification requirements.

[0009] The elemental analysis steps involve measuring the elements in the sample using X-ray spectroscopy and calculating the content comparison coefficients of Paleozoic characteristic elements according to a set calculation strategy.

[0010] The target identification step involves matching the content comparison coefficients of each identification feature element with the pre-set identification element standards to determine the Paleozoic species identification result of the current sample's strata.

[0011] In a preferred embodiment, the sampling area selection strategy set in the identification and selection step includes setting multiple sampling areas at different locations in the same stratum depth.

[0012] Furthermore, in one embodiment, the sample preparation step includes: removing well wall fragments from the collected base rock sample to control the content of well wall components in the rock sample.

[0013] In another embodiment, the sample preparation step further includes:

[0014] Fine rock fragments were selected as samples from the base rock sample;

[0015] The sample is thoroughly pulverized according to the set sample specifications, wherein the sample specifications include: a mass of not less than 10g and a particle size of not less than 200 mesh.

[0016] The pulverized sample is dried naturally or machine-dried according to the set requirements.

[0017] Based on a matching compression strategy, the dried sample is compressed to form a tablet sample with the required adhesion.

[0018] In an optional embodiment, prior to the elemental analysis step, the following is included:

[0019] The element calibration steps involve measuring and calibrating the elements contained in real Paleozoic strata, and selecting representative identification characteristic elements to formulate identification element standards corresponding to different strata and rock types.

[0020] The process of measuring and calibrating the elements includes the following operations:

[0021] Start the instrument in advance during the set time period before calibration to stabilize it;

[0022] X-ray spectral analysis was used to measure and calibrate all rock types contained in the well area.

[0023] Specifically, in one embodiment, during the measurement and calibration process using X-ray imaging spectroscopy based on all rock types contained in the well area:

[0024] Multiple samples of the same type of standard material are used for element content calibration, and each sample has multiple calibration samples. The correlation coefficient between the X-ray fluorescence pulse count of each element and the element content of the standard sample should be greater than 0.9.

[0025] In one specific embodiment, during the elemental analysis step, the content comparison coefficient of the identifying feature element x is determined according to the following algorithm:

[0026] C x =x max / x min

[0027] In the formula, C x Let x be the comparison coefficient of the content of the currently measured element x. max The highest content of element x in the current formation sample; x min This represents the lowest content of element x in the current formation sample.

[0028] In a preferred embodiment, Al, Fe, and Ti are selected as the identification feature elements. The identification element criteria used in the target recognition step include:

[0029]

[0030] Based on other aspects of any one or more of the above embodiments, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more of the above embodiments.

[0031] Based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a system for identifying Paleozoic strata based on elemental differences in overlying strata, the system being applied to perform the methods described in any one or more of the above embodiments.

[0032] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0033] This invention provides a method and system for identifying Paleozoic strata based on elemental differences in overlying strata. The method effectively identifies the depths that need to be sampled and those that do not by pre-executing a sampling area selection strategy. Once the set sampling area is reached, multiple volumes are automatically sampled at depth intervals, and then samples are prepared and identified simultaneously. This eliminates the need for batch identification and analysis, thus improving operational efficiency and reliability.

[0034] In addition, before performing elemental analysis and calculations, the collected samples are processed using precise sample preparation operations to avoid interference from false rock fragments, while improving the sample uniformity of X-ray spectral analysis and significantly enhancing the reliability of the analytical data.

[0035] Furthermore, this invention enables the preliminary identification of specific Paleozoic strata based on quantitative data calculation results. While ensuring accuracy, it also achieves a time advantage in identifying strata overlying limestone, allowing for advance acquisition of Paleozoic information and providing data support for drilling and construction adjustments in the current well.

[0036] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a flowchart illustrating a method for identifying Paleozoic strata based on elemental differences in overlying strata according to an embodiment of the present invention.

[0039] Figure 2 This is an elemental logging curve from well Da28-Xie1 in the method for identifying Paleozoic strata provided in this embodiment of the invention;

[0040] Figure 3 This is a detailed flowchart of the identification process of a method for identifying Paleozoic strata provided in an embodiment of the present invention;

[0041] Figure 4 This is an elemental logging curve from well Chegu 211 in another embodiment of the method for identifying Paleozoic strata provided by the present invention;

[0042] Figure 5 This is a schematic diagram of the structure of a system for identifying Paleozoic strata based on elemental differences in overlying strata, provided in another embodiment of the present invention. Detailed Implementation

[0043] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Those skilled in the art will then fully understand how the present invention uses technical means to solve technical problems and achieve technical effects, and will be able to implement the present invention specifically based on the above-described implementation process. It should be noted that, as long as there is no conflict, the various embodiments and features of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0044] Although the flowchart describes the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can terminate when its operation is complete, but it may also have additional steps not included in the diagram. A process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0045] Computer equipment includes user equipment and network equipment. User equipment or clients include, but are not limited to, computers, smartphones, PDAs, etc.; network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing consisting of a large number of computers or network servers. Computer equipment can operate independently to implement this invention, or it can connect to a network and implement this invention through interaction with other computer equipment in the network. The network in which the computer equipment is located includes, but is not limited to, the Internet, wide area network, metropolitan area network, local area network, VPN network, etc.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0047] Blocks containing ancient buried hill structures exhibit high stratigraphic complexity. For example, in fault-type ancient buried hill formations, the overlying strata are the Sha-1 and Sha-3 members, while the buried hill strata consist of Upper Paleozoic, Lower Paleozoic, and Archean strata. Due to the complex lithological assemblage and the existence of multiple intrusion modes, identifying the buried hill interface presents challenges. To accurately identify the buried hill interface, it is necessary to clarify the stratigraphic conditions during the drilling process of exploration wells in this block and employ matching intrusion modes for each well.

[0048] In recent years, the Lower Paleozoic buried hill oil and gas reservoirs in the Chezhen and Zhanhua depressions have become one of the main areas for increasing reserves and production in the Shengli Oilfield. This region is characterized by well-developed faults and complex strata. The overlying strata of the Paleozoic buried hills vary greatly, especially the Upper Paleozoic Benxi Formation and the Lower Paleozoic, both of which contain carbonate reservoirs, with visual differences so subtle they are difficult to distinguish. To ensure drilling safety and meet the needs of later development, it is necessary to expose 1-2 meters of the Lower Paleozoic strata and install technical casing.

[0049] Currently, the process typically involves technicians making a preliminary determination of the Paleozoic limestone layer based on stratigraphic parameters. Then, during drilling, sampling and observation are conducted to directly identify the Paleozoic buried hill features where the samples are located. However, drilling often employs new technologies such as PDC drill bits and turbine drills, resulting in fine rock cuttings and severe damage to the original morphology of fossils, structures, and textures in the rocks and minerals. This allows for the determination of lithology but not the differentiation of stratigraphic features, making it difficult to accurately determine the stratigraphic position of Paleozoic strata and complicating the identification of buried hill interfaces. Therefore, existing identification methods have poor representativeness, cannot accurately and reliably obtain classification results for deep Paleozoic strata, and have a high probability of interface interception during the identification process. Inaccurate manual predictions require multiple sample submissions for rock and mineral identification, delaying the drilling schedule. Furthermore, existing identification methods often conduct testing only after drilling into Paleozoic strata, only able to basically identify conventional strata from Paleozoic strata, unable to accurately determine the type of Paleozoic strata. This hinders the pre-adjustment of drilling parameters for different strata and easily leads to a high proportion of interference factors in the identification data.

[0050] To address the aforementioned problems, this invention provides a method and system for identifying Paleozoic strata based on elemental differences in overlying strata. Based on the Paleozoic overlying strata at corresponding depths during drilling, test samples are prepared using a set strategy. X-ray spectroscopy is used to measure and calculate the content contrast coefficients of characteristic elements, and the specific Paleozoic type of the strata to be drilled is determined by combining the calibrated elemental identification standards.

[0051] The following describes the detailed flow of the method according to an embodiment of the present invention with reference to the accompanying drawings, the steps of which can be executed in a computer system containing, for example, a set of computer-executable instructions. Although the logical order of the steps is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0052] Example 1

[0053] Figure 1 This diagram illustrates a flowchart of a method for identifying Paleozoic strata based on elemental differences in overlying strata, as provided in Embodiment 1 of the present invention. (Refer to...) Figure 1 As can be seen, the method includes the following steps.

[0054] A method for identifying Paleozoic strata based on elemental differences in overlying strata, characterized in that the method comprises:

[0055] In step S110 of the identification and selection process, before drilling, the true depth of the Paleozoic strata in different drilling areas is calculated. Based on the upper limit of the true depth, the corresponding overlying identification depth is set, and a corresponding sampling area selection strategy is formulated for different drilling areas according to the set depth interval.

[0056] Sampling step S120: During the drilling process, drilling cuttings are directly collected as basic rock samples according to the sampling area selection strategy of the current drilling area, and marked respectively; among them, the basic rock samples are marked based on the well number, sampling depth and azimuth signal;

[0057] Sample preparation step S130: Select and prepare the marked basic rock sample to form a sample that meets the identification requirements;

[0058] Elemental analysis step S140: Elemental measurements are performed on the sample using X-ray spectroscopy, and the content comparison coefficients of Paleozoic identification characteristic elements are calculated according to the set calculation strategy.

[0059] Target identification step S150: Match the content comparison coefficients of each identification feature element with the pre-set identification element standards to determine the Paleozoic species identification result of the current sample's strata.

[0060] Considering the diverse distribution patterns of strata and the existence of different strata types at different depths, in order to take into account the test results of rock samples from different orientations during drilling, in one embodiment, the sampling area selection strategy set in the identification and selection step includes: setting multiple sampling areas at different orientations of strata at the same depth.

[0061] Based on the sampling area selection strategy in step S110, after drilling reaches the set depth, rock cuttings from the Paleozoic limestone overlying strata or suspected overlying strata are collected. Elemental analysis is performed using an X-ray fluorescence spectrometer to measure the percentage content of each element, which serves as data for identifying the Paleozoic strata type.

[0062] In order to improve the accuracy of elemental analysis and calculation results, after collecting drilling cuttings in sampling step S120, this invention does not directly measure based on the drilling cuttings, but first efficiently forms a pellet sample based on a set sample preparation strategy for X-ray spectroscopy analysis.

[0063] Considering the application scenario, complete sample selection is difficult to implement. Firstly, it is difficult to distinguish between genuine and false rock fragments, making the removal of false rock fragments impossible. Secondly, under conditions of fine rock fragments, there are no technical means to perform complete sample selection. Through analysis and research, a scientific and feasible sample collection method was determined.

[0064] Therefore, in one embodiment, the sample preparation step includes: removing wellbore fragments from the collected base rock sample to control the content of wellbore components in the rock sample and reduce the interference of wellbore fragments on the subsequent sample preparation process. In other words, if wellbore fragments appear in the sample, they are considered false rock cuttings. Removing wellbore fragments in advance can effectively minimize the influence of false rock cuttings.

[0065] In practical applications, only the target rock cuttings need to be sampled. A strategy of screening large rock blocks and scanning small rock blocks combined with observation can be used to remove the rock fragments that have fallen off the wellbore.

[0066] To ensure the 100% representation of true rock fragments, the selected samples are not directly crushed or compressed. Instead, finely crushed true rock blocks or fragments are chosen as the target samples, crushed, and used to prepare the test specimens, thus ensuring the representativeness of the sample composition.

[0067] Therefore, in one embodiment, the sample preparation step further includes:

[0068] Fine rock fragments were selected as samples from the base rock sample;

[0069] The sample is thoroughly pulverized according to the set sample specifications, wherein the sample specifications include: a mass of not less than 10g and a particle size of not less than 200 mesh.

[0070] The pulverized sample is dried naturally or machine-dried according to the set requirements.

[0071] A matching compression strategy is used to compress the dried samples to form tablets with the required adhesion. During operation, it is important to ensure that the pulverizing module is thoroughly cleaned before and after each use to prevent cross-contamination of samples.

[0072] In addition, considering that there may be iron filings from drill wear or crushing equipment on the surface of rock blocks or rock cuttings, after obtaining the true rock cuttings crushed sample, the following steps are also taken: using a magnetic suction device to remove the iron filings, so as to avoid the iron filings affecting the measurement of the content of characteristic elements.

[0073] Since wet samples can affect elemental analysis by detecting elements in water or other liquids, and can also affect the normal operation and stability of X-ray spectroscopy instruments, the pulverized samples are dried before being pressed.

[0074] In addition, it should be noted that when drying pulverized samples, natural air drying should be used as much as possible. If oven drying is used, the oven temperature should be controlled below 80℃.

[0075] When pressing the dried sample, the following conditions must be met:

[0076] (1) When pressing rock samples, the pressure should not be less than 20 tons and the pressure should be held for 20 seconds to ensure the adhesion of the sample pieces and prevent them from falling off inside the instrument.

[0077] (2) For samples that are not easy to compress into sheets, a small amount of binder may be added. The binder should not contain elements with an atomic number greater than 11 (boric acid is recommended), and the name of the binder and the sample number should be noted.

[0078] (3) The tablet surface is flat and free of cracks or breaks;

[0079] (4) The tableting mold must be cleaned before each use to prevent cross-contamination of samples.

[0080] Researchers considered that the content standards for various elements in Paleozoic overlying strata of different rock types in different regions may vary, and therefore, it is necessary to pre-define corresponding identification standards to improve operational efficiency while ensuring the reliability of identification results. Therefore, before the elemental analysis step, the following steps are included:

[0081] The element calibration steps involve measuring and calibrating the elements contained in real Paleozoic strata, and selecting representative identification characteristic elements to formulate identification element standards corresponding to different strata and rock types.

[0082] The process of measuring and calibrating the elements includes the following operations:

[0083] Start the instrument in advance during the set time period before calibration to stabilize it;

[0084] X-ray spectral analysis was used to measure and calibrate all rock types contained in the well area.

[0085] Specifically, in one embodiment, during the measurement and calibration process using X-ray spectral analysis based on all rock types contained in the well site:

[0086] Multiple samples of the same type of standard material are used for element content calibration, and each sample has multiple calibration samples. The correlation coefficient between the X-ray fluorescence pulse count of each element and the element content of the standard sample should be greater than 0.9.

[0087] In practical applications, the following requirements must be met when calibrating elemental content using standard substances:

[0088] (1) The instrument should be turned on and stabilized for at least 1 hour in advance;

[0089] (2) The standard samples shall be national standard rock samples. The types of rock samples used should include all rock types in the well area. It is recommended that the types of rock samples used cover most common types of the three major rocks. The total number of standard samples should be no less than 10.

[0090] (3) Use no less than 5 standard substances of the same type to calibrate the element content. The correlation coefficient between the X-ray fluorescence analysis pulse count of the 12 elements and the element content of the standard sample should be greater than 0.9.

[0091] In addition, to avoid sample preparation and measurement errors caused by instrument malfunction, repeatability, stability, and linearity tests of standard material samples should be performed after each instrument reinstallation; repeatability and stability tests should be performed monthly; and stability tests should be performed once per work shift.

[0092] Furthermore, in the elemental analysis step S140, the elemental content in the sample is detected through the following operations:

[0093] (1) Before analyzing the sample, a vacuum should be drawn, and the vacuum level should be no less than 90%.

[0094] (2) Start the analysis when the vacuum level meets the requirements, and the analysis time should not be less than 60 seconds in principle;

[0095] (3) The parameter settings during sample analysis must be completely consistent with the parameter settings during instrument calibration.

[0096] (4) X-ray analysis, recording and output of 12 elements including Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn and Fe in rock cutting samples.

[0097] Based on the measured percentage content of each element, characteristic elements of elemental difference are identified. In a preferred embodiment, Al, Fe, and Ti are selected as identification characteristic elements in the elemental analysis step, and then the Paleozoic content comparison coefficients of characteristic elements Al, Fe, and Ti are calculated respectively.

[0098] Furthermore, in a specific embodiment, the content comparison coefficient of the identification feature element x is determined according to the following algorithm:

[0099] C x =x max / x min

[0100] In the formula, C x Let x be the comparison coefficient of the content of the currently measured element x. max The highest content of element x in the current formation sample; x min This represents the lowest content of element x in the current formation sample.

[0101] For example, the content comparison coefficient for element Al essentially represents the multiple of change in Al content in the overlying strata of Paleozoic limestone.

[0102] Taking the historical well with well number: Da 28-Xie 1 as an example, its elemental logging curve data is as follows: Figure 2 As shown in Table 1, the characteristic elemental contents of the Paleozoic overlying strata of this well are as follows:

[0103] Table 1. Characteristic Elements for Identification of Well Da 28-Xiang 1

[0104]

[0105] It should be noted that the strata in the table above refer to the actual measured rock fragments belonging to the Upper Paleozoic overlying strata and the Lower Paleozoic overlying strata; Al 上 The stratigraphic content correlation coefficient, i.e., the multiple of change in Al% of the strata overlying the Upper Paleozoic limestone: 6.17 / 6.16 = 1.001623376623377 ≈ 1.00

[0106] Al 下 Stratigraphic content correlation coefficient, i.e., the multiple of change in Al% of the strata overlying the Lower Paleozoic limestone:

[0107] 9.02 / 6.11 = 1.476268412438625 ≈ 1.48

[0108] For other identification feature elements, the same calculation method is used:

[0109] Formation content correlation coefficient C Fe 上 = The multiple of change in Fe% in the overlying strata of the Upper Paleozoic limestone;

[0110] Formation content correlation coefficient C Fe下 Fe = the multiple of Fe% variation in the overlying strata of the Lower Paleozoic limestone;

[0111] Formation content correlation coefficient C Ti 上 Ti = the percentage change in Ti percentage of the overlying strata of the Upper Paleozoic limestone;

[0112] Formation content correlation coefficient C Ti下 Ti = the percentage change in Ti% of the overlying strata of the Lower Paleozoic limestone;

[0113] It should be noted that the strata in the table above refer to the strata identified after measurement. The actual rock fragments measured belong to the Upper Paleozoic overlying strata and the Lower Paleozoic overlying strata.

[0114] Furthermore, such as Figure 3 As shown, based on the calculated Paleozoic content comparison coefficients of Al, Fe, and Ti elements, and according to the identification standard of Al, Fe, and Ti element stratigraphic content comparison coefficients corresponding to the rock types of the overlying strata in the area currently described by the well, the upper-lower Paleozoic stratigraphic interface is identified. Taking common Paleozoic buried hill carbonate rocks as an example, the identification element standards used in the target identification step include:

[0115] Table 2 Criteria for Identifying Elements

[0116]

[0117] When the correlation coefficients of Al, Fe, and Ti element content in the strata meet the identification criteria, the limestone beneath the current stratum is a matching Lower Paleozoic stratum.

[0118] Elemental logging of well D28-X1 revealed that the correlation coefficients for Al, Fe, and Ti elements in the Upper Paleozoic strata were 1.00, 1.09, and 1.01, respectively, while those in the Lower Paleozoic strata were 1.48, 1.91, and 2.12, respectively. The correlation coefficients for Al, Fe, and Ti elements in the Lower Paleozoic strata were significantly higher than those in the Upper Paleozoic strata, allowing for accurate and rapid identification of the Lower Paleozoic strata.

[0119] In contrast, elemental logging of well CG211 and analysis of the stratigraphic correlation coefficients for Al, Fe, and Ti revealed that the correlation coefficients for Al, Fe, and Ti in the Upper Paleozoic strata were 1.12, 1.01, and 1.19, respectively, while those in the Lower Paleozoic strata were 3.98, 4.77, and 2.20, respectively. The correlation coefficients for Al, Fe, and Ti in the Lower Paleozoic strata were significantly higher than those in the Upper Paleozoic strata, enabling accurate and rapid identification of the Lower Paleozoic strata.

[0120] Another implementation case: Taking Chegu 211 well as an example

[0121] (I) Based on the cuttings selection spacing requirements in the geological design document, systematic cuttings samples were collected. Samples were analyzed, data collected, and calculated according to the X-ray elemental logging technical operation standards. The elemental logging curves of Well Chegu 211 are shown below. Figure 4 As shown in Table 3 below, the element identification measurement table is as follows;

[0122] Table 3. Element Table of Chegu 211 Well

[0123]

[0124] It should be noted that the strata in the table above refer to the strata identified after measurement. The actual rock fragments measured belong to the Upper Paleozoic overlying strata and the Lower Paleozoic overlying strata.

[0125] (II) Calculation of the comparison coefficient: For details of the elemental content comparison coefficient (multiple) of Chegu 211 well, please refer to Table 4 below:

[0126] Al 上 Stratigraphic content correlation coefficient: Al = Al% variation factor of the overlying strata of the Upper Paleozoic limestone:

[0127] 7.22 / 7.18 = 1.005571030640669 ≈ 1.00

[0128] Al 下 Stratigraphic content correlation coefficient: Al = Al% variation factor of the strata overlying the Lower Paleozoic limestone:

[0129] 6.77 / 1.42 = 4.767605633802817 ≈ 4.77

[0130] Fe 上 Stratigraphic content correlation coefficient: Fe = multiple of Fe% variation in the overlying strata of Upper Paleozoic limestone

[0131] 5.77 / 6.49 = 1.124783362218371 ≈ 1.12

[0132] Fe 下 Stratigraphic content correlation coefficient: Fe = multiple of Fe% variation in the overlying strata of the Lower Paleozoic limestone

[0133] 12.82 / 3.22 = 3.981366459627329 ≈ 3.98

[0134] Ti 上 Stratigraphic content correlation coefficient: Ti = multiple of Ti% variation in the overlying strata of the Upper Paleozoic limestone

[0135] 0.62 / 0.52 = 1.192307692307692 ≈ 1.19

[0136] Ti 下 Stratigraphic content correlation coefficient: Ti = (Multiple of Ti% variation in the overlying strata of the Lower Paleozoic limestone)

[0137] 0.90 / 0.41 = 2.195121951219512 ≈ 2.20

[0138] Table 4. Element Multiples of Well Chegu 211

[0139]

[0140] Then, the stratigraphic content correlation coefficients of Al, Fe, and Ti elements are compared with the corresponding identification element standards to identify the depth of the upper-lower Paleozoic stratigraphic boundary.

[0141] The scheme provided in the above embodiments of the present invention utilizes X-ray elemental logging technology to quantitatively identify the interfaces of lower Paleozoic buried hills. By measuring the formation content of characteristic elements in prepared sheet samples and calculating content comparison coefficients, Paleozoic strata can be rapidly pre-identified at the logging site using the Al, Fe, and Ti elemental content comparison coefficients. This overcomes the problems of significant sample noise, long processing times, and insufficient accuracy in existing identification techniques. The present invention, based on the overlying strata of Paleozoic strata for pre-identification, can not only identify lithology but also effectively quantify elemental data to identify specific Paleozoic strata categories, providing timely and reliable data support for real-time drilling and well completion operations.

[0142] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0143] It should be noted that, in other embodiments of the present invention, the method can also be combined with one or more of the above embodiments to obtain a new Paleozoic stratigraphic identification method.

[0144] It should be noted that, based on the methods in any one or more embodiments of the present invention described above, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more embodiments. When the program code is executed by the operating system, it can implement the method for identifying Paleozoic strata based on the elemental differences of the overlying strata as described above.

[0145] Example 2

[0146] The methods described in the above-disclosed embodiments of the present invention are detailed. These methods can be implemented using various forms of apparatus or systems. Therefore, based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a system for identifying Paleozoic strata based on elemental differences in overlying strata. This system is used to execute the method for identifying Paleozoic strata based on elemental differences in overlying strata described in any one or more of the above embodiments. Specific embodiments are given below for detailed description.

[0147] Specifically, Figure 5 The diagram shows a schematic representation of the structure of a system for identifying Paleozoic strata based on elemental differences in overlying strata, as provided in an embodiment of the present invention. Figure 5 As shown, the system includes:

[0148] The identification and selection module 51 is configured to, before drilling, count the true depth of Paleozoic strata in different drilling areas, assign corresponding overlying identification depth based on the upper limit of the true depth, and formulate corresponding sampling area selection strategies for different drilling areas according to the set depth intervals.

[0149] The sampling module 53 is configured to directly collect drilling cuttings as basic rock samples during the drilling process according to the sampling area selection strategy of the current drilling area, and mark them respectively;

[0150] The sample preparation module 55 is configured to select and prepare the marked basic rock sample to form a sample that meets the identification requirements.

[0151] The elemental analysis module 57 is configured to perform elemental measurements based on the sample using X-ray spectroscopy and to calculate the content comparison coefficient of Paleozoic identification characteristic elements according to a set calculation strategy.

[0152] The target identification module 59 is configured to match the content comparison coefficient of each identification feature element with the pre-set identification element standard to determine the Paleozoic species identification result of the current sample's stratum.

[0153] Furthermore, in one embodiment, the sampling area selection strategy set by the identification and selection module includes setting multiple sampling areas at different locations within the same stratum depth.

[0154] In a preferred embodiment, the sample preparation module is configured to perform the following operations:

[0155] From the collected basic rock samples, fragments of the well wall are removed to control the content of well wall components in the rock samples.

[0156] Furthermore, in one embodiment, the sample preparation module is specifically configured to prepare sheet-like samples through the following operations:

[0157] Fine rock fragments were selected as samples from the base rock sample;

[0158] The sample is thoroughly pulverized according to the set sample specifications, wherein the sample specifications include: a mass of not less than 10g and a particle size of not less than 200 mesh.

[0159] The pulverized sample is dried naturally or machine-dried according to the set requirements.

[0160] Based on a matching compression strategy, the dried sample is compressed to form a tablet sample with the required adhesion.

[0161] In an optional embodiment, the system further includes an element calibration module 56, which is configured to pre-measure and calibrate the elements contained in the real Paleozoic strata, and select representative identification feature elements to formulate identification element standards corresponding to different strata and rock types.

[0162] Specifically, the element calibration module measures and calibrates the elements contained in the formation through the following operations:

[0163] Start the instrument in advance during the set time period before calibration to stabilize it;

[0164] X-ray spectral analysis was used to measure and calibrate all rock types contained in the well area.

[0165] Furthermore, when the element calibration module performs measurement calibration using X-ray imaging spectral analysis based on all rock types included in the construction well area, it follows these principles:

[0166] Multiple samples of the same type of standard material are used for element content calibration, and each sample has multiple calibration samples. The correlation coefficient between the X-ray fluorescence pulse count of each element and the element content of the standard sample should be greater than 0.9.

[0167] In a preferred embodiment, Al, Fe, and Ti are selected as the identification feature elements, and the element analysis module specifically determines the content comparison coefficient of the identification feature element x according to the following algorithm:

[0168] C x =x max / x min

[0169] In the formula, C x Let x be the comparison coefficient of the content of the currently measured element x. max The highest content of element x in the current formation sample; x min This represents the lowest content of element x in the current formation sample.

[0170] In an optional embodiment, the target recognition module uses the following criteria for identifying elements:

[0171]

[0172] In the system for identifying Paleozoic strata based on elemental differences in overlying strata provided in this invention embodiment, each module or unit structure can operate independently or in combination according to actual measurement and calculation needs to achieve the corresponding technical effects.

[0173] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0174] The phrase "an embodiment" in the specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0175] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for identifying Paleozoic strata based on elemental differences in overlying strata, characterized in that, The method includes: Before drilling, the actual depth of Paleozoic strata in different drilling areas is statistically analyzed. Based on the upper limit of the actual depth, the overlying identification depth is set accordingly. Sampling area selection strategies are formulated for different drilling areas according to the set depth intervals. During the sampling process, drilling cuttings are directly collected as basic rock samples according to the sampling area selection strategy of the current drilling area, and then marked. The sample preparation steps include selecting and preparing marked basic rock samples to form samples that meet the identification requirements. The elemental analysis steps involve measuring the elements in the sample using X-ray spectroscopy and calculating the content comparison coefficients of Paleozoic characteristic elements according to a set calculation strategy. The target identification step involves matching the content comparison coefficients of each identification feature element with the pre-set identification element standards to determine the Paleozoic species identification result of the current sample's strata. In the elemental analysis step, the content comparison coefficient of the identifying characteristic element x is determined according to the following algorithm: In the formula, This is the comparison coefficient for the content of element x currently being measured. This represents the highest content of element x in the current formation sample. This represents the lowest content of element x in the current formation sample; Al, Fe, and Ti are selected as the identification feature elements. In the target identification step, the criteria for these identification elements include: 。 2. The method according to claim 1, characterized in that, In the identification and selection step, the sampling area selection strategy includes setting multiple sampling areas at different orientations of the same stratum depth.

3. The method according to claim 1, characterized in that, The sample preparation step includes: removing well wall fragments from the collected base rock sample to control the content of well wall components in the rock sample.

4. The method according to claim 3, characterized in that, The sample preparation step further includes: Fine rock fragments were selected as samples from the base rock sample; The sample is thoroughly pulverized according to the set sample specifications, wherein the sample specifications include: a mass of not less than 10g and a particle size of not less than 200 mesh. The pulverized sample is dried naturally or machine-dried according to the set requirements; Based on a matching compression strategy, the dried sample is compressed to form a tablet sample with the required adhesion.

5. The method according to claim 1, characterized in that, Prior to the elemental analysis step, the following is included: The element calibration steps involve measuring and calibrating the elements contained in real Paleozoic strata, and selecting representative identification characteristic elements to formulate identification element standards corresponding to different strata and rock types. The process of measuring and calibrating the elements includes the following operations: Set a time period before calibration to turn on the instrument to stabilize it; X-ray spectral analysis was used to measure and calibrate all rock types contained in the well area.

6. The method according to claim 5, characterized in that, During the measurement and calibration process using X-ray spectral analysis based on all rock types included in the well construction area: Multiple samples of the same type of standard material are used for element content calibration, and each sample has multiple calibration samples. The correlation coefficient between the X-ray fluorescence pulse count of each element and the element content of the standard sample should be greater than 0.

9.

7. A storage medium, characterized in that, The storage medium stores program code capable of implementing the method as described in any one of claims 1 to 6.

8. A system for identifying Paleozoic strata based on elemental differences in overlying strata, characterized in that, The system is used to perform the method as described in any one of claims 1 to 6.

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